Thomas Bolton Gilchrist Septimus Dalziel was an English engraver known chiefly for his illustrations of the work of Charles Dickens.

Thomas Dalziel was the youngest of The Brothers Dalziel, a prolific wood-engraving business in Victorian London, founded in 1839 by George Dalziel.

Thomas produced many illustrations for books published by the family firm. Many of his designs are considered by Philip Allingham (Faculty of Education, Lakehead University, Thunder Bay, Ontario) to be workmanlike rather than anything more inspired, although he considers Thomas Dalziel's illustrations for Bunyan's Pilgrim's Progress and The Arabian Nights to be above average.